We plan to study the basic physiology of bile formation, including the biophysic of solute and H20 transport between blood and bile, the intrahepatic distribution and metabolism of materials destined for biliary excretion, and the operation of neural and hormonal control mechanisms. Specific goals for the period covered by the present proposal are to identify the mechanism of bile salt-independent choleresis induced by SC-2644 to describe the kinetics of bile salt exchange in isolated liver cells, to evaluate the role of micellar sequestration in promoting canalicular excretion of organic anions, and to define by autoradiography the steady-state intralobular distribution of bile salts arriving in the afferent blood supply.